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Figure 3
Concurrent processing of femtosecond crystallography data at LCLS with cctbx.xfel. A file-mediated approach is taken in which the data-acquisition system multiplexes the detector images to several serial-access binary streams written in extended tagged container (XTC) format (a). For data analysis, each of the six XTC files is assigned to a separate 12-core Linux node, on which the pyana framework reads the data within a single master process and delegates the analysis of consecutive images to as many as 11 child processes. pyana provides a Python-language callback hook to be executed once for each image, into which is inserted the cctbx spotfinder code. As the XTC file is on a shared-disk file system, data acquisition and processing are performed simultaneously. Although processing lags behind acquisition for any given XTC file, the `run' is switched after a few minutes to a new XTC file, so the overall processing throughput roughly keeps up. (b) Bragg spot counts/image are shown for a 70 min 483 845-image thermolysin data set (Sierra et al., 2012BB49) broken into 12 runs starting at the indicated wall clock times. The hit rate (defined as the fraction of images with ≥16 Bragg spots within a defined area) is plotted over a 5 s sliding window. The total number of hits is 15 094.

Journal logoBIOLOGICAL
ISSN: 1399-0047
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